EAGER: Exploring Links between Iron and Phosphorus Nutrition of Antarctic Marine Phytoplankton

浮游植物是生长在阳光照射的海洋表面的微观单细胞植物。在南极洲周围的南大洋，浮游植物生活在次优条件下，因为海水中的铁含量不足以生长。此外，南大洋浮游植物的化学组成与其他海洋区域不同，磷的比例高于其他元素，这一特点最终影响到全海洋营养物质的分布。研究人员假设，南大洋浮游植物的高磷成分是由它们的低铁含量造成的。具体来说，他们假设富含磷的分子植酸是由浮游植物合成的，以帮助将铁储存在指定的细胞隔室中，如液泡。最近的观察表明，一些浮游植物可以吸收植酸，这表明它可能是由某些物种产生的。植酸在土壤中无处不在，它有助于通过植物根系吸收铁，同样可以帮助南大洋的浮游植物通过细胞膜获得铁。该项目有利于国家科学基金会的目标，即提高对南大洋和全球海洋之间相互作用的认识，通过关注南极特有的浮游植物物种，扩大对南极生物群和相关过程的基本知识。作为该项目的一部分，康涅狄格大学文理学院海洋科学系将赞助招聘、重新安置和指导一名理科人数不足的研究生，该项目旨在确定南大洋浮游植物的不寻常元素组成是否是贫血的结果。这项工作将质疑肌醇六磷酸（植酸）是否有助于南极浮游植物获得和储存铁，导致细胞磷相对于其他元素的比例升高。包括一名研究生在内的研究人员将用从南大洋分离的浮游植物菌株进行实验室培养实验。他们将在缺铁和含铁的培养基中培养细胞，看看缺铁条件下细胞的磷含量是否更高。他们将测试在足够磷的条件下生长的细胞是否获得更多的铁，使它们在缺铁条件下比在缺磷条件下生长得更好。他们还将询问在缺铁条件下生长的细胞是否在植酸存在下获得更快的生长速度。该奖项反映了NSF的法定使命，通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Phytoplankton are microscopic single-celled plants that grow at the sun-lit surface of the ocean. In the Southern Ocean around Antarctica, phytoplankton live in sub-optimal conditions because the amount of iron in seawater is insufficient for growth. Moreover, the chemical composition of Southern Ocean phytoplankton is distinct from that in other ocean regions, with a higher proportion of phosphorus relative to other elements, a characteristic that ultimately influences the distribution of nutrients ocean-wide. The researchers hypothesize that the high phosphorus composition of phytoplankton in the Southern Ocean is caused by their low iron content. Specifically, they postulate that a phosphorus-rich molecule, phytic acid, is synthesized by phytoplankton in order to assist in the storage of iron in designated cellular compartments, such as vacuoles. Recent observations show that some phytoplankton can absorb phytic acid, suggesting that it may be produced by certain species. Phytic acid is pervasive in soils, wherein it aids absorption of iron via plant roots and could similarly help phytoplankton in the Southern Ocean acquire iron via the cell membranes. This project benefits the National Science Foundation's goals of improving understanding of interactions between the Southern Ocean and the global ocean, of expanding fundamental knowledge of Antarctic biota and associated processes by focusing on phytoplankton species unique to the Antarctic. As part of this project, the Department of Marine Sciences from the College of Liberal Arts and Sciences at the University of Connecticut will sponsor the recruitment, relocation and mentorship of a graduate student under-represented in the sciences.This project aims to determine whether the unusual elemental composition of phytoplankton at the Southern Ocean is a result of anemia. The work will query whether inositol hexakisphosphate (phytic acid) aids Antarctic phytoplankton acquire and store iron, resulting in an elevated fraction of cellular phosphorus relative to other elements. The researchers, including a graduate student, will conduct laboratory culture experiments with phytoplankton strains isolated from the Southern Ocean. They will grow cells in iron- deficient versus iron-replete media to see if their phosphorus content is higher in iron-deficient conditions. They will test whether cells grown with sufficient phosphorus acquire more iron, allowing them to grow better in iron-deficient conditions than cells deriving from phosphorus-poor conditions. They will also query whether cells grown in iron-deficient conditions achieve faster growth rates in the presence of phytic acid. Results will inform the design of CRISPR mutants with which to investigate phosphorus and iron co-metabolism in Antarctic marine phytoplankton.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.